1. Field of the Invention
This invention relates to stable Factor VIII formulations. More particularly, high purity Factor VIII protein is formulated in high ionic strength media for administration to patients suffering from hemophilia type A.
Antihemophilic factor or Factor VIII procoagulation activity protein (hereinafter Factor VIII) functions to correct the clotting defect in hemophilia type A plasma. Accordingly, Factor VIII preparations are extensively used for the purpose of supplying Factor VIII to hemophilic patients.
2. Description of the Prior Art
An important concern associated with the use of Factor VIII and other therapeutic agents derived from biological sources is the transmission of diseases, especially viral diseases. Prevalent viral contaminants include hepatitis B virus (HBV), non-A, non-B hepatitis virus (NANBV), and HTLV III/LAV/HIV which cause AIDS. In order to ensure that products produced from biological sources are virus-safe, various methodologies have been proposed for virus inactivation. However, most plasma protein preparations are unstable and require special care to prevent denaturation, alteration and loss of activity during the virus inactivation process. One approach to prevent denaturation and other alteration of plasma proteins utilizes additives during the pasteurization process. Representative examples follow.
U.S. Pat. No. 4,440,679 (Fernandes et al.) describes a method wherein therapeutically active proteins are pasteurized by mixing the protein composition with a pasteurization-stabilizing amount of a polyol prior to pasteurization.
U.S. Pat. No. 4,297,344 (Schwinn et al.) discloses a process for the stabilization against heat of the coagulation factors II, VIII, XIII, antithrombin III and plasminogen in aqueous solution, which comprises adding to the solution both an amino acid and one or more of a monosaccharide, an oligosaccharide or a sugar alcohol.
U.S. Pat. No. 4,585,654 (Landaburu et al.) pertains to a process of inactivating viruses in plasma protein solutions by heating the same in the presence of a polyol, a surface active agent and a chelating agent.
U.S. Pat. No. 4,446,134 (Naito et al.) is drawn to a virus-inactivating process in which Factor VIII is heated in an aqueous solution in the presence of one principal stabilizer of neutral amino acids, monosaccharides, oligosaccharides, and sugar alcohols and an auxiliary stabilizer of salts of hydrocarbon and hydroxyhydrocarbon carboxylic acids.
These processes aim at destroying the potential viral and bacterial infectivity of the preparations while substantially maintaining their desired biological activity. As such, they represent significant steps toward the provision of satisfactory plasma protein products to patients.
However, in order to be administrable, the plasma protein products need to be formulated with suitable compounds, lyophilized for storage and ready for reconstitution. Before formulating, the additives used during the pasteurization process are removed and their stabilizing/protecting effect is no longer present to prevent loss of activity. Applicants have encountered degradation problems with Factor VIII both during lyophilization and upon reconstitution with normal saline solution.
The inventors have extensively studied the problem of degradation in order to provide effective Factor VIII formulations for injection. A highly purified Factor VIII was used to study degradation occurring during lyophilization and reconstitution such as that produced by the teaching of U.S. Pat. No. 4,361,509 and U.S. Pat. Re. 32,011. The method there disclosed provides for about one thousand-fold purification of Factor VIII obtained from a commercial concentrate using an antibody column. The subsequent purification step by an Aminohexyl-Sepharose column chromatography further increases purity by 2 to 3-fold resulting in Factor VIII activity of about 2,300 units per mg of protein. Elution of Factor VIII from said Aminohexyl-Sepharose is accomplished by the use of a calcium chloride solution having a concentration of from 0.25 to 0.5M. This solution, while being eminently potent for the treatment of hemophilia type A, is less than satisfactory for two reasons: first, having such a high calcium chloride concentration, it is not suitable for injection to the patient; and second, upon lyophilization, a drastic loss of Factor VIII occurs.
To remedy the problems, an isotonic solution was prepared by dialyzing Factor VIII contained in said calcium chloride solution against 0.15M sodium chloride, 5 mM calcium chloride and 3 mM histidine at pH 6.8. Upon testing, a drastic loss of Factor VIII was again observed.
It has now been discovered that highly purified Factor VIII can be formulated with physiologically acceptable compounds for stabilization against loss of activity during storage in a liquid state, lyophilization, storage in the lyophilized state and reconstitution preceding administration to patients.